Census 2010. The decennial census has traditionally started in the fall of the year '04 preceeding the decennial census.
By way of Federal Register announcement
of the 2010 Census Redistricting Data Program, the Census Bureau
commences preparation for Census 2010.

Role and Scope. As the Federal agency responsible for the year 2000
decennial census of population and housing, the Census Bureau maintains
a great wealth of information regarding details and the status of various
developments. Click here
to view an index to some of this information via the Census Bureau Internet
site.

The Census 2000 Data Access and Use web pages augment the
information on Census 2000 provided by the Census Bureau by adding other
types of information, news, and perspectives focused on data access and use.

Focus of the Census 2000 Data Access and Use web pages is on:

news on data releases by the Census Bureau,

descriptive information about Census 2000 data products and public data use resources,

linkage of Census 2000 data with data from other decennial programs,
most notably the 1990 census, other Federal statistical data, primary data
(your data) and other secondary data sources are key areas of interest

Census 2000 data access issues in other Federal agencies,

availability of data access and user support resources supplemental to
those of the Census Bureau, and

Title 13 of the U.S. Code requires that the apportionment counts--the
resident population totals for each state--be delivered to the President
within 9 months of the census date. In the 1990 and most 20th Century
censuses, the census date has been April 1, meaning that the Office of
the President received the counts by December 31 of each census year.
Within a week of the opening of the next session of the Congress,
the President must report to the Clerk of the House of Representatives
the census counts for each state and the number of Representatives to
which each jurisdiction is entitled.
Within 15 days, the Clerk of the House informs each state Governor of the
number of Representatives to which each state is entitled. The legislatures
in each state are responsible for geographically defining the
boundaries of their congressional and other election districts--the
redistricting process which requires more detailed census data.

Public Law 94-171, which amended the Census Law (Title 13, U.S. Code),
was enacted by Congress in 1975, and guides the Census 2000 redistricting
data program. The purpose of this law is to provide state legislatures
with small-area census population totals for legislative redistricting.
However, there is a broader interest in the P.L. 94-171 data products
that extends beyond the stated purpose of the law due to (1)
the use of these data in other types of apportionment and redistricting
and (2) these data being the first data to become available from
the Census. More information is available on the Census
Internet site.

Implications of Census 2000 Data and Reapportionment

Article 1, Section 2, of the United States Constitution states:

"Representatives and direct Taxes shall be apportioned among the several
States which may be included within this Union, according to their
respective Numbers...The actual Enumeration shall be made within three
Years after the first Meeting of the Congress of the United States,
and within every subsequent Term of ten Years, in such Manner as
they shall by Law direct."

Therein lies the primary mandate of the U.S. census, apportionment of
the House of Representatives.
Since that first census in 1790, five methods of apportionment have been used.
The current method used, the Method of Equal Proportions, was adopted in
1941 following the census of 1940. This method assigns seats in the House
of Representatives according to a "priority" value. The priority value is
determined by multiplying the population of a State by a "multiplier."
For example, following the 1990 census, each of the 50 states was given
one seat out of the current total of 435.
The next, or 51st seat, went to the State with the highest priority value
and thus became that State's second seat. This continued until all
435 seats had been assigned to a state.

To view the mechanical aspects of this process, you may look
at the
spreadsheet that enables you to see
state-by-state how additional seats are assigned.

Census 2000 Data and Redistricting More Generally. While the
foregoing description of the role of Census 2000 in Congressional
reapportionment and redistricting, Census 2000 data will be widely used
in other types of redistricting applications. These redistricting applications
include redistricting state legislatures, other types of
statewide geographic area redistrictings, marketing and service areas,
school districts (attendance areas and election areas), police beats,
fire districts, environmental-related management areas,
city election districts, and other types of geography.
See Redistricting Resources and Operations
for more information about redistricting software, data, processes, and
applications.